Sealing disk having a tab

ABSTRACT

The invention relates to a sealing disk ( 20 ) for a closure of a container ( 10 ) having an opening ( 11 ) delimited by a circumferential edge ( 12 ), wherein the sealing disk comprises several layers having an edge. A group ( 30 ) of lower layers ( 31, 32, 33, 34, 35 ) closes the opening ( 11 ) of the container ( 10 ) before the first opening thereof. Said group ( 30 ) can be sealed onto the circumferential edge ( 12 ) of the opening ( 11 ) by means of a sealing layer ( 31 ). The group ( 30 ) is detachably connected to a group ( 40 ) of upper layers ( 41, 42, 43, 44 ). The opening ( 11 ) of the container ( 10 ) can be closed again temporarily using the second group ( 40 ). The sealing disk ( 20 ) comprises at least one grip tab ( 50 ), which is formed only by one or more of the layers from the first group ( 30 ) of the lower layers.

The invention relates to a sealing disk for a container closure for use with a container having an opening delimited by a circumferential edge, in which the sealing disk comprises several layers having an edge, of which a group of lower layers tightly closes the opening of the container prior to the initial opening of the container, in which the group of lower layers can be sealed by means of a sealing layer onto the circumferential edge of the opening, in which the group of lower layers can be joined in a detachable manner to a group of upper layers of the sealing disk, in which the opening of the container can then be closed again temporarily by the group of upper layers, in which the sealing disk has at least one gripping tab, in which the gripping tab is formed only by one or several of the layers from the group of lower layers, and in which the layers forming the gripping tab project over the edge of the other layers flatly by the surface of the gripping tab.

Containers serve for receiving contents, for example, for taking up liquids or powder-form food products or other substances. Containers have an opening or a mouth part. It is frequently desired or even necessary to close this container mouth part with a disk-shaped seal, which tightly seals the content against external influences.

There are several reasons for the requirement of this tight seal. On the one hand, the content will be protected against any disruptive influence from the outside, for example, against the penetration of water vapor or oxygen; on the other hand, its aroma will remain intact. There is another reason in the case of filling with aggressive materials: a protection against leakage that is as optimal as possible must be assured. Finally, an authenticity protection for commercial sales can also be provided by such a seal, since the user can immediately discern whether anyone has previously manipulated the contents of the container.

Additionally, the container opening is then closed with a screw cap or a similar element, which provides for the mechanical and stable closing of the container mouth part outside the disk-shaped seal. The actual disk-shaped seal is a flexible thin film in this case. Upon initial use after purchase, the user unscrews the screw cap and breaks the film in order to gain access to the content of the container. After this, he closes the container again, as long as he has not yet removed the entire content. This repeated closing is carried out by now screwing the screw cap—without the film that in the meantime has been broken and removed—onto a corresponding counter-thread on the mouth part of the container. The screw closure can optionally close the now breached content, possibly for a time span not as long as the original closure configuration, but for a time span satisfactory to the user, since he can now control it himself.

The film that seals the container contents is introduced by means of induction sealing, as is known, for example, from EP 0 717 710 B1. For this purpose, a complete sealing disk is applied, whose lowermost layer forms the sealing layer. A metallic second layer, usually comprising aluminum and which serves for the heat coupling and transfer during the induction process and optionally forms an additional mechanical protection, is applied over the lowermost layer. The second layer is solidly combined with the first layer in a well conducting manner, particularly for heat transfer. These layers form a group of lower layers. Additional layer-form components of the sealing disk, which remain in the cap when the screw cap or other rotating closure is opened, are then provided above the mentioned aluminum layer.

These other layers of the sealing disk remaining in the cap form a group of upper layers, and are simultaneously those elements that provide for a very good closure again upon a repeated closing of the screw cap after the breaking and removal of the group of lower layers produced with the initial opening, even though the authenticity seal and also the original tightness are lacking after this repeated closing.

A constant problem with such closures that are both reliable and well-proven is the initial opening by the user or consumer. During the initial opening, a breaking of this film or group of lower layers found on the mouth part of the container by a knife or even by the finger of the user, on the one hand, is not always possible or hygienic for all container contents, and on the other hand, residues of film are left behind on the edge of the opening of the container, which can adversely affect the later pouring or shaking out of the container contents.

In order to make the opening process more convenient for the user and also safer for further use, the user is provided with a handle or grabbing piece for pulling off the film. This grabbing piece can be a folded piece that springs up for the user to grab and then pull off the film, as proposed in EP 1 181 211 B1 or WO 00/66453 A1.

It is more common, and for example, is known from DE 39 20 324 A1 and EP 0 408 217 A1, to provide the sealing disk with a gripping tab that springs out, which then can be gripped by the user outside the edge of the mouth part of the container and be pulled up, so that the entire film is detached from the container edge.

This very simple and convincing design by itself, however, has the disadvantage that the gripping tabs are disrupted when the screw cap is screwed on, since they must be accommodated in suitable form in the thread and in the screw cap. On the one hand, there is little space available there, and, on the other hand, these gripping tabs can also adversely affect the function of the screwing process. Conversely, the gripping tabs may also be damaged by the screwing process or in the most unfavorable case, the entire sealing disk can be adversely affected in its sealing function.

In order to reduce the problems with the gripping tabs projecting into the thread of the screw cap, for example, it is proposed in DE 1 482 575 A1, U.S. Pat. No. 4,722,447 and EP 0 697 345 B1, to equip the sealing disks not with just one, but with several outwardly projecting gripping tabs. In this way, a rather symmetric and thereby reduced distribution will be achieved. The problem is not solved, of course, but only redistributed.

Another approach is selected in proposals from EP 0 668 221 B1, GB 2 330 134 A, JP 2000-191021 A and DE 10 2007 014 084 B3. Here, the sealing disks are equipped with gripping tabs, in which the thickness of the gripping tab is less than the thickness of the other surface regions of the sealing disk. This is achieved by the fact that, of the several layers of the sealing disk, only one layer or a few layers also form(s) the gripping tabs.

Due to the fact that the tabs of the sealing disk are formed very thin, they are far more flexible for accommodating in the remaining empty spaces inside the screw cap and the screw-cap thread. The risk of mutual disruption of the individual elements when closing the package or also during the opening process is thus considerably reduced.

Now, a transfer of these concepts into practice has been successfully carried out at least with the production method for these types of sealing disks proposed in DE 10 2007 014 084 B3.

The idea is also already known from GB 2 330 134 A and JP 2000-191021 A as well as the subsequently-published EP 2 045 194 B1, to form the gripping tab that is thus reduced in its thickness and is therefore very thin only from the uppermost layer or layers of the group of lower layers and not to allow it to project radially outward into the region of the inner thread of the screw cap, but rather, either to bend it first by 90° upward and then once more by 90° in the direction toward the central point of the sealing disk, as in JP 2000-191021 A, and in this way to guide and accommodate it in a free space inside the screw cap cover, or, however, as in GB 2 330 134 A and in one embodiment of EP 2 045 194 B1, to fold it by 180° and lie it on top of itself, so that after the screw cap is unscrewed, the gripping tab lies free for use by the consumer.

The design from JP 2000-191021 A has the disadvantage that now, in fact, although the gripping tab no longer engages in the thread of the screw cap or of the container, it now lies in a region above the upper group of layers and thus in the region which will remain in the screw cap when the latter is screwed on, in order to make possible a further closing. There is thus now a considerable risk that the gripping tab will jam in this region below the screw cap above this so-called “reseal” part and thus will tear upon opening and therefore lead to the unwanted disadvantages that are precisely to be avoided.

Further practical disadvantages arise in GB 2 330 134 A. Thus, a folding of the combination gripping tab that includes the metallic layer on it could disrupt the induction sealing properties of the entire combination gripping tab, since a double aluminum layer is present in part of the region of the otherwise circular symmetric arrangement because of this, and this considerably changes the induction properties.

The same disadvantages arise in the second embodiment of the subsequently published EP 2 045 194 B1. This embodiment first folds the gripping tab with all layers by 180° on the upper side of the sealing disk and then folds it a second time back on itself by 180°. On the one hand, this has the disadvantage that the sealing disk possesses a triple thickness in the region of the gripping tab and thereby is also mechanically very non-uniform and an adhering to a reseal part, for example, is made very difficult, but also in the region of the gripping tab, the aluminum layer is formed as a triple layer, and thus also leads to a strong asymmetry of the induction properties.

In one embodiment of GB 2 330 134 A, one attempts to avoid this problem by moving the metallic layer used for induction into the reseal part, thus into that part that is used for the further closure. This is very impractical, since this aluminum layer is just not suitable for this purpose, for being used continually on a container mouth part with repeated closing and opening actions.

Another disadvantage consists in the fact that when the container and the container closures are disposed of, an aluminum layer in a plastic screw cap represents a foreign component, which is generally undesired. Plastic and aluminum are to be disposed of separately as much as possible. Any remaining aluminum layer in the screw caps is thus ecologically undesirable, since it makes recycling difficult and thus might encounter rejection by concerned consumers.

Another problem may occur in both the sealing disks according to GB 2 330 134 A as well as JP 2000-191021 A, and the first embodiment of EP 2 045 194 B1 and also for other sealing disks, which operate with such back folds of 90° or 180°, and, in fact, this problem may arise due to the fact that a considerable notching effect occurs precisely in the edge region between a folded layer and the adjacent, unfolded layer. This notching effect leads to a force that tries to detach the different layers of the sealing disk from one another.

Grasping the tab could thus lead to the circumstance that the layer provided with the tab detaches from the other layers and does not open the container, or does not open it as desired, or that parts of the combined layers detach from one another in an unanticipated manner or tear.

This behavior when the container is torn open by means of a tab is perceived by users as unpleasant and unreliable and is rejected. It should be considered that a user then is not only annoyed in this single instance, but his rejection generally extends to the corresponding product line of the container packager, and he may refrain from the purchase of such goods in future instances, so that the image of the producer of the contents of the containers that are thus packaged may also be tarnished.

The problem of the present invention is thus to propose a sealing disk with which the described problems can be avoided as much as possible.

This problem is solved according to the invention with a sealing disk as initially described, in that the layer of the group of lower layers that lies closest to the sealing layer forms the gripping tab, and in that the surface part of this layer projecting over the edge of the other layers is folded around the outer edge of all other layers of the group of lower layers with the exception of the sealing layer and is applied flat on top of the uppermost of the group of lower layers and is covered by the group of upper layers, so that the gripping tab can be gripped after detaching the group of upper layers in the initial opening of the container.

Alternatively, it is also possible not only to form the layer adjacent to the sealing layer in the appropriate form, but also to similarly form several layers lying on top of one another directly adjacent to the sealing layer.

The problem presented for the invention can be surprisingly solved in a very simple way. Another arrangement of the sequence of the individual layers and a special formation of these layers leads to the circumstance that, on the one hand, a tab is formed that has a clearly reduced thickness in comparison to the entire sealing disk and only contributes to a thickening in a part of the region that does not matter optically and technically for the entire combined system of the sealing disk, even when there is a folding back into the circular circumference, and that, on the other hand, a notching effect can no longer occur. The other disadvantages described in connection with the prior art also no longer occur.

According to the invention, the lowermost layer of the sealing disk following on top of the sealing layer and apart from the sealing layer itself, is formed in such a way that it projects outwardly over the edge, beyond the other layers of the sealing disk. This very thin layer is then bent upward first by 90° and guided past all other layers that belong to the group of lower layers that only close the container mouth part prior to the initial opening. Above the uppermost of these layers, the gripping tab is then folded again by 90° in the direction toward the center of the container and applied flat onto the uppermost of these layers. On top of this layer, which occupies only a part of the surface, is first found the separating layer, which separates the upper group and the lower group of layers from one another in the initial opening, and on top of this are found all layers of the upper group.

First of all, this has the consequence that prior to its use, in the operation of filling the container, the sealing disk has the form of a conventional, circular, flat sealing disk and also can be treated as such. A particular alignment on the container is not necessary, since the sealing disk is outwardly symmetric.

The disk is also not essentially thicker than conventional disks, since only the layer placed between the other layers and later forming the gripping tab is added, or optionally another also very thin layer is added, which will be explained in the following preferred embodiments.

The container also need not be treated differently than it has been previously for the initial opening or for the later openings by the user. After screwing on the screw cap, the upper group of layers, which remain as the reseal parts of the screw cap just as they did previously, are separated by and at the separating layer, and the lower group of layers, which remain on the opening of the container, thus the container mouth part, seal and close this mouth part at this time, just as they did previously.

Of course, unlike in the previous designs, a gripping tab is now applied centrally on the remaining part of the sealing disk, on top of the uppermost layer of the lower group, and is freely accessible to the user. The user need only take this gripping tab and pull it toward him, which needs no further explanation. By pulling, force is exercised on the edge of the lower group of sealing disks* and, in fact, directly on the lowermost layer of this lower group of layers, this lowermost layer being adjacent to the sealing layer, since the gripping tab was made from this layer precisely, prior to the folding. *sic; sealing layers?—Translator's note.

With this pull, the sealing layer immediately yields and the pull on the gripping tab thus simultaneously removes everything above this lower layer adjacent to the sealing layer, therefore the complete lower group of the sealing disk with one pull. The container is thus opened.

Further procedures would then be possible just as in the case of conventional re-closing actions, due to the unchanged upper group of layers, thus due to the reseal part in the screw cap.

Based on this description, it is clear that a similar process is also possible, not only when the lowermost layer directly adjacent to the sealing layer is folded in appropriate form and is formed for the gripping tab, but also when two or more directly adjacent subsequent layers of the sealing disk can be folded.

It is particularly preferred in this case if a thin layer of a material that is resistant to tearing and is also simultaneously lightweight, is additionally inserted between the metallic layer providing for the induction and the melting sealing layer providing for the seal. This additional layer further preferably forms the gripping tab.

It is particularly preferred if this additionally inserted thin layer comprises a tear-resistant, but simultaneously lightweight material of polyethylene terephthalate (PET). Layers made of this material increase the tensile strength. This is important not only in connection with the gripping tab, but increases the tensile strength of the combined layer system containing the metallic layer that particularly comprises aluminum. The aluminum layer as such is not particularly resistant to tearing for the most part, so that combining it with such a thin tear-resistant PET layer is also of advantage in another respect.

This additionally inserted layer of polyethylene terephthalate would about a notching effect if it were arranged above the metallic layer. If this additional plastic film with the gripping tab formed thereon is then turned up and in, an inevitable separation movement is formed between this additional layer and the metallic layer lying thereunder. This notching effect, however, will be avoided according to the invention.

Above the metallic layer, the further layer sequence can be produced as desired each time for the particular case. In general, an adhered separating layer will be disposed here, which is strong enough to hold together the sealing disk in the resting state, but will yield so that the joining will be eliminated right at this place when a screwing process occurs.

On top of this separating layer, a support layer or foam layer is provided, which remains in the screw cap during the screwing process, and when it is closed again, provides for sealing for a certain amount of time.

The gripping tab made of the additionally inserted layer is now folded around the metallic layer in this embodiment, and is then folded first in the direction of the axis of the circular sealing disk. The adherent layer is thus found above this tab.

When the container is closed, the induction sealing process is not adversely affected by the additional layer. In fact, the metallic layer, which, for example and preferably comprises aluminum, is clearly heated by the induction and the eddy currents produced thereby, and it delivers this heat also to this additional layer, which is directly adjacent to it on the side facing the container. The stability of this layer is not adversely affected by this heat, however, and it delivers the heat flow directly to the subsequent sealing layer. The latter melts in turn, as intended, particularly in the edge region, and thus provides for the sealing to the edge of the mouth part of the container.

After cooling, the sealing layer now therefore seals the compound layer system lying over it opposite the container mouth part, thus at first opposite the additional layer.

In the initial opening process, the consumer unscrews the screw cap and thus detaches the connection through the separating layer. The upper parts of the sealing disk above this adherent layer remain in the screw cap.

This means that the consumer now directly looks at the tab, which lies bent around the metallic layer on top of this metallic layer, ready to grip.

Therefore, the consumer and user also immediately recognizes this gripping tab: it can be colored or also configured in another way so that it clearly stands out optically or in another form from the layers lying thereunder. In a particularly simple manner, the gripping tab can be colored in a striking signal color, e.g., in the company color of the producer of the container contents, and/or by printing the company logo or trademark on the gripping tab.

The size of the gripping tab is less critical than in conventional designs, since there is no longer the danger that it will disrupt the function of the screw thread of the screw cap.

The gripping tab can thus project up to the center of the sealing disk or it may also possess complicated or ergonomically and haptically pleasing shapes.

It would even be conceivable to allow the gripping tab to assume a shape that either possesses a meaningful relationship to the product itself, thus, for example, it may have the stylized form of a coffee cup or of a piece of pastry, or in turn, even the form of a company logo.

If still further layers should be provided above the aluminum layer for a special application purpose, e.g., a layer used for printing or the like, the tab thus also lies above these layers and is also bent around these layers.

If the user now grips this tab, which is not adhered or otherwise fastened onto the now uppermost layer adjacent to it, then the user can pull the tab [and remove] all the still present layers of the sealing disk from the mouth part of the container by exercising an appropriate manual force and thus can break open the seal. Pulling the tab pulls off all the layers above the additional layer at one time without an additional manipulation upward and there is no danger that not all of these layers will be removed by the pull on the tab, by gripping and pulling once.

The single layer that was found underneath the additional layer, adjacent to the edge of the container, was the sealing layer; this is precisely broken open, however, by this force without anything further, so that notching effects need not be considered here.

Further preferred features are indicated in the subclaims.

A production of this sealing disk according to the invention is possible, preferably with the method proposed in DE 10 2007 014 084 B3.

An example of embodiment of the invention will be presented in more detail below on the basis of the drawing. Herein:

FIG. 1 shows a perspective exploded view of a container with a mouth part having a sealing disk;

FIG. 2 shows a top view onto a closed container having a sealing disk according to an embodiment of the invention after unscrewing the screw cap;

FIG. 3 shows a section through a first embodiment of the invention;

FIG. 4 shows a section through another embodiment of the invention with the omission of several elements;

FIG. 5 shows a section through a third embodiment of the invention with the omission of several elements;

FIG. 6 shows a section through a fourth embodiment of the invention with the omission of several elements;

FIG. 7 shows a section through a sheet of film for producing an embodiment according to FIG. 6; and

FIG. 8 shows a section through a sheet of film for producing another embodiment according to FIG. 6.

The mouth part of a container represented in FIG. 1 shows the region of an opening 11 of a container 10. This can be a bottle, a container for agricultural chemicals, a container to be closed in an aroma-tight manner, for example, for powdered coffee, or a similar container. The opening 11 is surrounded by a circumferential edge 12. The edge 12 is generally circular.

A sealing disk 20 that comprises several layers and that is closed at the top and on the side by a cover 15, in particular a screw cap with a screw cap base unit is found on this opening 11 after filling the container 10 but prior to opening it for the first time.

The sealing disk 20 has approximately the same diameter as the opening 11 with the edge 12 of the container 10. The sealing disk 20 is sealed on the circumferential edge 12 by means of a sealing layer 31, which will be explained in more detail below, and which is not yet easily seen in the exploded representation in FIG. 1.

The sealing disk 20 comprises two groups 30 and 40 of layers. The first group 30 contains those layers of the sealing disk 20 that lie directly on the edge 12 of the container 10 when the container has still not been opened, and upon a first opening of the container 10, in particular upon a first unscrewing or removal of the cover 15 from the container 10, remain on the mouth part of the container, thus on the opening 11. After the first unscrewing of cover 15, thus afterward just as before, they block the user's access to the content of the container 10.

The user removes this lower group 30 of layers of the sealing disk 20 from the opening 11 after the initial opening of the container 10 and then gains access.

Due to the circumstance that this lower group 30 of layers of the sealing disk 20 is still found on the opening 11 of the container 10 when the container is first opened, the user can reliably conclude that no one before him has used this container 10 and has removed content or has added unauthorized substances to the content of the container 10. This lower group 30 therefore forms a type of authenticity seal.

In addition, a long-lasting sealing of the container contents against the external environment is also obtained by the seal, which safeguards, e.g., the aroma found inside the container, and reliably prevents the entry of oxygen, water vapor or microorganisms even over several years. The lower group 30 of the layers of the sealing disk 20 thus also has the task of preserving and protecting the contents of the container.

The upper group 40 of the layers of the sealing disk 20 is formed of those layers that remain in the cover 15 when the container 10 is first opened. These layers are thus removed together with the cover 15 during the first unscrewing and the user no longer needs to remove them separately from the opening 11 of the container. This upper group 40 forms the so-called “reseal” part. After the user has obtained access to the content of the container 10 for the first time by removing the lower group 30 of layers of the sealing disk 20 and, for example, has removed part of the contents thereof, the user would usually like to store the remaining content of container 10 in order to again access it later. For this purpose, he screws cover 15 onto the now free opening 11 of container 10.

In fact, now that the lower group 30 of layers of the sealing disk 20 is missing, the upper group 40 of layers, thus the reseal part as mentioned, is now applied, however, onto the edge 12 of the opening 11 of the container 10 and in turn closes this opening.

No secure sealing occurs now in fact, although these upper layers of the group 40 are configured so that they can assure a sealing of the substance contents of the container 10 against the external environment over a long period of time, although this is not guaranteed, as was the case prior to the initial opening. Also, protection against unauthorized manipulation of the container content is no longer provided, but now the container is usually found in the possession and in the household of an end user, so that this function indicating an untouched condition is no longer required.

In order to be able to separate the groups 30 and 40 from one another during the initial opening, the lowermost layer of the upper group 40 is formed as the separation layer 41. This separation layer 41 comprises a material, which in fact holds together the layers of the lower group 30 and of the upper group 40 of the sealing disk 20 during the manufacturing process and the closing of the container by the packager or bottler of the container 10 and usually further also holds these together during the entire manipulation of the container prior to the initial opening of the cover 15, whereby the adhering effect is dimensioned sufficiently small, however, so that the upper group 40 can be lifted from the lower group 30 when an opening procedure of the cover 15 is performed.

Usually, a polymer separating layer, for example, of polyethylene or polypropylene film, or a wax-like material, will be used for this purpose.

Yet another layer 34 of the lower group 30 of layers of the sealing disk 20 is also indicated in FIG. 1. A metallic layer 34 is involved here, which serves for introducing induction heat, in order to melt the sealing layer 31 and thus to guide a secure seal onto the edge 12 of the opening 11 of the container 10 during the filling process of the container 10.

Further layers and details will be explained in the following.

First, however, now observe in FIG. 2 a mouth part of a container 10, from which the cover 15 has just been unscrewed or otherwise removed. As a result of this, the upper group 40 of layers of the sealing disk 20 with the cover 15 is also no longer to be seen and one is looking at the lower group 30 of layers of the sealing disk 20, which are still sealed, just as they were before, on the circumferential edge 12 of the opening 11 of the container 10. The removal of this lower group 30 from the edge 12 thus has not yet occurred at the moment presented in FIG. 2.

The observer thus obliquely views the uppermost layer 35 of the lower group 30 of layers of the sealing disk 20. A gripping tab 50 lies flat on top on this uppermost layer 35. This gripping tab 50 possesses a different coloring or another property by means of which it is clearly set apart from the uppermost layer 35 of the lower group 30 and immediately catches the eye of the user.

Gripping tabs 50 in conventional sealing disks projected outward over the edge 12 of the opening 11 of the container 10 and were gripped there and then removed.

The gripping tab 50 in the embodiment according to the invention presented here, however, lies flat on top of the uppermost layer 35 of the lower group 30 lying thereunder. It is not joined in its surface area with this layer lying directly under it, but is applied loosely. There is still a joining only at the edge of the sealing disk 20, which will be explained in more detail in the following.

The user can thus easily lift the gripping tab 50 at its flat part and grip it and pull on it.

If the user pulls on the gripping tab 50, then he exercises force upward on the edge of the lower group 30 of the sealing disk 20, overcomes the sealing force of the sealing layer 31 on the edge 12 of the opening 11 of the container 10 and at this site pulls off the lower group 30 upward from the mouth part of the container.

The adhesion properties of the different layers, for example, of the sealing layer 31, are thus adjusted so that without great effort, the user can pull off the entire lower group 30 of the sealing disk 20 from the edge 12 of the opening 11 of the container 10 with one pull on the gripping tab 50. The sealing force, however, is high enough that opening will still not result if only the cover 15 containing the upper group 40 of the layers of the sealing disk 20 is unscrewed, as described above.

Special attention must be paid, however, to the connection of the tab or gripping tab 50 to the lower group 30 of the sealing disk 20. One should not bind this gripping tab 50 to the uppermost layer 35 of the lower group 30 or form the uppermost layer 35 itself so that it projects over the circumference of the other layers of the sealing disk 20 and projects out from the circumferential edge 12 of the opening 11 of the container 10 and then simply fold the surface segment of the uppermost layer 35 projecting out over this edge 12 and fold it back on itself. This leads to considerable notching effects between this uppermost layer 35 and the layers of the lower group 30 lying thereunder. The uppermost layer 35 then has the tendency to detach from the other layers and thus the integrity of the entire sealing disk 20 becomes questionable. This notching effect may occur in the manipulation of the sealing disk itself, prior to its introduction onto the container 10, but it will especially occur later.

Several possibilities for a detailed construction will be explained in more detail in the following figures.

A section through a first embodiment of a sealing disk according to the invention is schematically shown in FIG. 3. Container 10 is to be imagined on the bottom and cover 15 on the top; both of these have been omitted for clarity here. The sealing disk 20 is also shown partially pulled apart in order to be able to better identify the lower group 30 and the upper group 40.

Viewed from container 10, the disk 20 begins first with a sealing layer 31. A layer 32 adjacent to the sealing layer 31 follows on top of this sealing layer 31. In the embodiment shown, this layer 32 is simultaneously a metallic layer 34. The layer 32 adjacent to the sealing layer 31 is not necessarily the metallic layer 34, and in most of the embodiment examples it is not; the reference numbers refer to the same layer only in the embodiment of FIG. 3.

This metallic layer 34 is simultaneously an induction layer, usually made of aluminum. This induction layer or metallic layer 34 provides for transferring heat produced in layer 34 by means of induction to the sealing layer 31 and thus solidly sealing it on the edge 12 of the opening 11 of the container 10 in the process of producing or packaging the container 10.

In this embodiment, the uppermost layer 35 of the lower group 30 of layers of the sealing disk 20 follows next on top of the induction layer or metallic layer 34.

The upper group 40 made up of the upper layers of the sealing disk 20 begins above this uppermost layer 35. A separating layer 41 can be seen first. This separating layer separates the upper group 40 from the lower group 30 during the initial opening. This layer involves a polymer separating layer, for example, a polypropylene or polyethylene film or a wax-like substance. The layer 41 comprises bonding agents and/or separating layers, for example, which bind the lower layers 31 to 35 with the other layers lying above layer 35, but make possible a separation during the opening process.

A polymer separating layer is preferably used as a bonding agent for the layer 41. A definitive adhesion, which can be predicted to be very good, can be obtained with a polymer separating layer. It should be considered that this layer must adhere temporarily, but in the case of a rotating movement during an opening procedure, it must make possible a separation of the layers of lower group 30 lying underneath from the above-lying layers that will be explained further in the following.

A layer 42 is found above layer 41. Layer 42 is a polypropylene film or a layer of high-density polyethylene (HDPE). On top of this is found a foam layer 43. It may comprise polyethylene foam or polypropylene foam, or in some cases of application, it may also comprise cardboard. In certain frameworks, this springy, resilient layer provides for the tight closure of the opening 11 of the container 10 when container 10 is re-closed after its initial opening.

Then another plastic film 44, e.g., of polypropylene or polyethylene (HDPE) is provided as the uppermost layer. If the foam layer 43 comprises cardboard material, it is possible to omit layers 42 and 44, thus both plastic films of HDPE, in particular.

This upper group 40 of the upper layers of the sealing disk 20 is also called the reseal part. In the originally closed container 10, the reseal part or this upper group 40 lies directly on the layer 35.

All layers of the two groups 30 and 40 of the sealing disk 20 are joined together very solidly including the layers 32 to 35, since they are no longer separated and need not be separated from one another.

The total thickness of all layers of the lower group 30 is very small in relation to the other dimensions of the container and also the opening, usually being related to the thickness of the reseal part, thus the layers of the upper group 40.

It can be recognized further that the layers 31, 32 or 34 and 35, respectively, not only form a flat layer, but that at the edge of the sealing disk 20, these layers are folded back to the center of the sealing disk 20. It should be noted that the thickness of the layers and the dimensions as well as also the relative relationships are not correct to scale, but are presented purely schematically.

The uppermost layer 35, which would be a plastic film here, preferably of polyethylene terephthalate, is folded back on itself in this case. The layers lying under it elsewhere in the layer sequence lie above it in this small folded region. The uppermost layer of this folded region is thus a part of the sealing layer 31.

This region of the uppermost layer 35 [of this folded part or ripping tab] is not flatly adhered by its entire surface to the upper side of the uppermost layer 35 of the lower group 30, but lies loosely on it.

Since a thickening is therefore present on this side of the sealing disk 20, the separating layer 41 is adapted to it and leaves space here for the uptake of this additional material. Since the separating layer 41 is a polymer separating layer or a wax-like substance, this is possible without any problem.

An alternative to this is shown in FIG. 4. A layer 33 made of a plastic film is additionally inserted between the metallic layer 34, which preferably comprises aluminum and serves as the induction layer, and the sealing layer 31. This plastic film preferably comprises polyethylene terephthalate.

Unlike in FIG. 3, here this layer 33 is equally the layer 32 adjacent to the sealing layer 31, while the metallic layer 34 is equally the uppermost layer 35 of the lower group 30 of layers of the sealing disk 20.

The layer 33 of polyethylene terephthalate, which here forms the layer 32 following the sealing layer 31, has an additional, positive effect. Whereas aluminum is in general not resistant to tearing, this resistance can be achieved in a very practical manner with a plastic film, in particular, of polyethylene terephthalate (PET). The combined system of the lower layers with the aluminum layer 34 and the additional layer 32 is thus resistant to tearing overall, which is very advantageous for this unit of the lower group 30 of layers.

The upper group 40 is omitted here, since it corresponds exactly to the design of the embodiment of FIG. 3.

On the right side, it can be seen that in this case, the sequence of the folded layers is different than in the representation of FIG. 3. The gripping tab 50 here has the layers: sealing layer 31, plastic film 33 and metallic layer 34 in this sequence from top to bottom, these layers lying on the upper side of the uppermost layer 35.

The representation of FIG. 4 is rendered slightly modified in FIG. 5. Since the sealing layer 31 is provided for sealing onto the edge 12 of the opening 11 of the container 10, it is relatively sticky, which in some circumstances is not desired in the region for the gripping tab. This could be disruptive both in the handling by the user as well as in the defined separating effect of the directly adjacent separating layer 41 of the two groups 30 and 40.

For this case, in an embodiment of this type, or also in other embodiments, correspondingly, the side of the sealing layer 31 directed upward may be provided with an additional protective coating 38 or a protective film 38.

The sealing layer 31 is not necessary or desired in the region of the gripping tab 50, since it contributes little or nothing at all to the tensile strength of the material. Of course, it frequently will be simpler in terms of manufacturing technology to fold the sequence of layers of the lower group 30 as a whole and not to omit specified regions. It should be noted that the sealing disks are punched out of large sheets and that in this case, small areas around the region of a sealing disk can be executed in complicated form under certain circumstances. It can therefore be simple to additionally apply a protective coating here or to cover this region of the sealing layer 31 above the gripping tab 50 in another way during the production of the sealing disk.

A variant is shown in FIG. 6, in which the sealing layer 31 is actually omitted on the folded upper side of the lower group 30 that forms the gripping tab 50.

Likewise, in this embodiment, it is also provided to allow the metallic layer 34 to end at the edge of the sealing disk, and therefore not to fold it back and not allow it to run out into the gripping tab 50.

This embodiment thus has a great advantage in that the induction that is introduced into the sealing disk is more uniform. In the embodiments of FIGS. 3, 4 and 5, it can be recognized that an overall thicker metallic region is formed, which could correspondingly also need to take up more heat, which should be compensated for correspondingly in the induction sealing. This is avoided from the outset in the embodiment of FIG. 6.

In this embodiment also, a notching effect cannot occur between the plastic film 33 provided with the gripping tab 50 (simultaneously, the layer 32 adjacent to the sealing layer 31) and the other layers, thus here the metallic layer 34. The tab 50 surrounds the outer edge of the metallic layer 34 and the notching effect can only occur between the plastic film 33 and the sealing layer 31, where it is specifically desired.

The representation in FIG. 6 specifically shows a particularly preferred embodiment.

Also, in the representation of FIG. 6, care is taken that the gripping tab 50 which is formed particularly thin here is not solidly adhered onto the upper side of the uppermost layer 35 of the lower group 30 of layers of the sealing disk 20.

It is shown in FIG. 7 how a sheet of film roughly in cross section could appear, from which sealing disks are folded and punched out for an embodiment according to FIG. 6.

FIG. 8 shows a modified variant of the embodiment of FIG. 6, in which, in fact, the sealing layer 31 runs out into the gripping tab 50, but not the metallic layer 34.

When container 10 is opened for the first time by unscrewing the cover 15 with the screw cap, the connection in the separating layer 41 between the layers 35 and 42 is broken. This can be produced in different ways. It is appropriate to keep the upper group 40 freely rotatable in the closure, thus in the screw cap 15, but, e.g., to hold it by projections or lifting pieces, so that when the screw cap 15 is rotated, the layers of the group 40 are pulled vertically upward and thus are separated from the layers of group 30.

Another, less preferred, but basically possible form consists in first carrying out a connecting of the reseal part, thus group 40, to the underside of the screw cap 15, so that when screw cap 15 is rotated, there occurs also a rotating motion of the layers of group 40 relative to the layers of group 30, which leads to the separation.

After the first opening of the screw cap 15 in both cases, i.e., in the embodiment of FIG. 8, in which the layers of the group 40 are pulled vertically upward as well as also in the basically possible form, in which a rotating motion separates the layers, the uppermost layer 35 of the lower group 30 lies in front of the user. The user then grips the gripping tab 50 and thus pulls all layers of the group 30 in one pull from the edge 12 of the opening 11 of the container 10.

In all embodiments of FIG. 8, the occurrence of notching effects between the layer with the gripping tab 50 and other layers is thus also completely avoided; only a separation of the lower group 30 from the sealing layer 31 or a separation within the sealing layer 31 occurs. The group 30 of lower layers thus remains intact and is pulled off as a whole without leaving behind residues on part of the surface of opening 11 of the container or also without surface separations due to the notching effect being able to occur.

A repeated screwing on of the cap 50* leads to the circumstance that the layer 42 of the reseal part comes to lie on the edge 12 of the opening 11 of the container 10 and seals it again. *sic; cap 15?—Translator's note.

In those embodiments in which an additional, conventionally absent layer 33 made of a plastic film is inserted between the metallic layer 34 and the sealing layer 31, this layer 33 then forming the layer next to layer 32, an additional layer now lies between the layer mediating induction heat and the sealing layer itself. However, this is comparatively easy to take into consideration, since only a small distance, which is slightly enlarged by the thickness of a thin plastic film, is present between the metallic layer and the sealing layer 31 to be heated. Slightly more induction heat will be required. The difference is minimal, of course, since it involves only a few pathways for losing the heat generated.

LIST OF REFERENCE CHARACTERS

-   10 Container -   11 Opening of the container -   12 Circumferential edge of the opening -   15 Cover, in particular screw cap -   20 Sealing disk -   30 Group of lower layers of the sealing disk -   31 Sealing layer -   32 Layer adjacent to the sealing layer -   33 Layer of plastic film, in particular polyethylene terephthalate -   34 Metallic layer, in particular aluminum -   35 Uppermost layer of the lower group -   38 Protective coating or protective film -   40 Group of upper layers -   41 Separating layer -   42 Plastic film, e.g., polypropylene or polyethylene -   43 Foam layer -   44 Plastic film, e.g., polypropylene or polyethylene -   50 Gripping tab 

1. A sealing disk for a container closure for use with a container having an opening delimited by a circumferential edge, in which the sealing disk comprises several layers with an edge, of which a group of lower layers tightly closes the opening of the container prior to the initial opening of the container, in which the group of lower layers can be sealed by means of a sealing layer onto the circumferential edge of the opening, in which the group of lower layers can be joined in a detachable manner to a group of upper layers of the sealing disk, in which the opening of the container can then be closed again temporarily by the group of upper layers, in which the sealing disk has at least one gripping tab, in which the gripping tab is formed only by one or several of the layers from the group of lower layers, and in which the layer forming the gripping tab projects beyond the edge of the other layers of the two groups flatly by the surface of the gripping tab, hereby characterized in that the layer of the group of lower layers adjacent to the sealing layer forms the gripping tab, and that the surface part of this layer that projects beyond the edge of the other layers is folded around the outer edge of all other layers of the group of lower layers with the exception of the sealing layer and is applied folded flat on top of the uppermost layer of the group of lower layers and is covered by the group of upper layers, so that the gripping tab can be gripped after detaching the group of upper layers in the initial opening of the container.
 2. A sealing disk for a container closure for use with a container having an opening delimited by a circumferential edge, in which the sealing disk comprises several layers with an edge, of which a group of lower layers tightly closes the opening of the container prior to the initial opening of the container, in which the group of lower layers can be sealed by means of a sealing layer onto the circumferential edge of the opening, in which the group of lower layers can be joined in a detachable manner to a group of upper layers of the sealing disk, in which the opening of the container can then be closed again temporarily by the group of upper layers, in which the sealing disk has at least one gripping tab, in which the gripping tab is formed only by one or several of the layers from the group of lower layers, and in which the layers forming the gripping tab project beyond the edge of the other layers flatly by the surface of the gripping tab, hereby characterized in that several layers of the group of lower layers lying next to the sealing layer form the gripping tab, and that the surface part of these layers that projects beyond the edge of the other layers is folded around the outer edge of all other layers of the group of lower layers with the exception of the sealing layer and is folded flat on top of the uppermost layer of the group of lower layers and is covered by the group of upper layers, so that the gripping tab can be gripped after detaching the group of upper layers for the initial opening of the container.
 3. The sealing disk according to claim 1, further characterized in that the layer adjacent to the sealing layer is a layer made of a plastic film, and in that the layer following this layer is a metallic layer as an induction layer.
 4. The sealing disk according to claim 3, further characterized in that the layer adjacent to the sealing layer comprises polyethylene terephthalate (PET).
 5. The sealing disk according to claim 3, further characterized in that the layer adjacent to the sealing layer is completely or partially colored.
 6. The sealing disk according to claim 1 further characterized in that the surface parts that project beyond the other layers and that are folded and applied flat onto the uppermost layer of the group of lower layers, are covered on top by a protective coating or a protective film.
 7. The sealing disk according to claim 2 further characterized in that the layer adjacent to the sealing layer is a layer made of a plastic film, and in that the layer following this layer is a metallic layer as an induction layer.
 8. The sealing disk according to claim 7, further characterized in that the layer adjacent to the sealing layer comprises polyethylene terephthalate (PET).
 9. The sealing disk according to claim 8, further characterized in that the layer adjacent to the sealing layer is completely or partially colored.
 10. The sealing disk according to claim 2, further characterized in that the surface parts that project beyond the other layers and that are folded and applied flat onto the uppermost layer of the group of lower layers, are covered on top by a protective coating or a protective film. 